Smelting process of low-carbon high-sulfur free cutting steel

Abstract

The invention relates to a smelting process of low-carbon high-sulfur free cutting steel. The smelting process comprises the following steps: (1) stirring after converter tapping, wherein the content of end-point oxygen required for converter tapping is less than or equal to 600 ppmm; (2) de-slagging firstly and then tapping; (3) enabling a refining slag system to be Al2O3-CaO-SiO2 and controlling the alkalinity to be 1.5-2.5; (4) performing precipitation and deoxidization in the refining process by adopting an aluminum line and a calcium line, feeding no aluminum line to deoxidize within 10-15 minutes before ladle hanging; (5) blowing argon for 3-5 minutes after deoxidization alloying and then fixing oxygen and entering a static mixing stage after the oxygen content is 20-50 ppm; (6) adopting covering slag and a low-carbon covering agent in the continuous casting process and ensuring the quality of a casting blank, wherein the degree of superheat is 20-40 DEG C, the quantity of water in a crystallizer is 90-120 m<3>/h, and the specific water flow is 0.6-0.9 L/kg. The smelting process provided by the invention has the benefits that the difficulty of a production process of the low-carbon high-sulfur free cutting steel can be solved, the stable flow control in the pouring process is ensured, the continuous pouring time is 10 h or above, and the yield is improved while the quality of the casting blank is ensured.

Description

technical field [0001] The invention relates to a method for smelting low-carbon high-sulfur steel, in particular to a smelting process for low-carbon high-sulfur free-cutting steel with excellent billet quality. Background technique [0002] The slagging and deoxidation process in the refining process of free-cutting steel is very important to the stable control of sulfur and oxygen content. Improper control of the oxygen level in high-sulfur steel under the high-temperature removal condition will easily cause refractory materials to corrode, resulting in poor flow control in the continuous casting production process. stable, the liquid level fluctuates frequently, which is likely to cause slag rolling and less flow stoppage, and affect the quality of the slab; low-carbon high-sulfur steel is a crack-sensitive steel type, and improper workmanship may easily cause defects such as internal cracks and surface depressions in the slab, and even appear Steel breakout and other pr...

AI Technical Summary

Problems solved by technology

[0002] The slagging and deoxidation process in the refining process of free-cutting steel is very important to the stable control of sulfur and oxygen content. Improper control of the oxygen level in high-sulfur steel under the high-temperature removal condition will easily cause refractory materials to corrode, resulting in poor flow control in the continuous casting production process. stable, the liquid level fluctuates frequently, which is likely to cause slag rolling and less flow stoppage, and affect the quality of the slab; low-carbon high-sulfur steel is a crack-sensitive steel type, and improper workmanship may easily cause defects such as internal cracks and surface depressions in the slab, and even appear Production accidents such as steel breakout